Known connection methods for connecting between plural data processing apparatuses included in a data processing system include indirect connection methods that connect between data processing apparatuses through an external designated router, and direct connection methods that directly connect together respective data processing apparatuses. In a direct connection method, plural data processing apparatuses are each provided with a router section that communicates with the respective data processing apparatuses performing computation, and the plural data processing apparatuses are connected together through a communication network (direct network).
A communication protocol in communication between data processing apparatuses is for example hierarchized as illustrated in FIG. 21.